This term is often used to describe programs involving aircraft to extending their in-service life in a manner that does not compromise flight safety.
[1] A typical program would involve the installation of strain gauges to measure loads, accelerometers to measure g-force and other parameters to support the program or to add value (such as flap position, aircraft altitude, environmental conditions etc.
[3] Unlike Health and Usage Monitoring Systems, OLM programs are generally a short term project used to assess the remaining useful safe life of an airframe.
OLM program's benefits include a possible increased safe operating life figure and helping to prevent accidents such as the C-130 crash that occurred after the platform had been modified and flown for a different mission (fire fighting).
There are several active OLM programs currently underway, including research initiatives to standardize approaches for civilian aircraft.